Gas mask



FIG. 1 is a front elevational view of a gas mask showing our new design;

FIG. 2 is a right side elevational view thereof;

FIG. 3 is a rear elevational view thereof;

FIG. 4 is a left side elevational veiw thereof;

FIG. 5 is a top plan view thereof;

FIG. 6 is a bottom plan view thereof;

FIG. 7 is a cross sectional view thereof; and

FIG. 8 is a top and front perspective view thereof.

The ornamental design for a gas mask, as shown and described.